ORAL. PRESENTATION 90 N.A.S.A.'S PLANETARY CARTOGRAPHY TEN-YEAR PLAN: 1993-2003 James R. Zimbelman Center for Earth and Planetary Studies, MRC $15, National Air and Space Museum, Smithsonian Institution, Washington, D.C. 20560, U.S.A. (Fax: 202-786-2566; Internet: [email protected]) Abstract Spacecraft exploration during the last 25 years has transformed our view of the planets and natural satellites in the solar system. The National Aeronautics and Space Administration (NASA) charged the Planetary Cartography Working Group (PCWG) to provide advice on cartographic opportunities and methods anticipated to result from on-going and future spacecraft missions. In February of 1994 the PCWG published a ten-year plan that outlined several recommendations and priorities for NASA's planetary cartography activities through 200$. The main recommendations of the ten-year plan are summarized in this paper. The primary motivation behind the recommendations in the report is that the goal of planetary mapping is to provide complete frames of reference for all subsequent studies of planetary objects. As planetary missions become more inter­ national in scope, it is important to develop an open dialogue between the international scientific and cartographic communities so that planetary maps will have the widest possible use in the most consistent and easily interpreted formats. 1 Introduction The advent of spacecraft exploration of the solar system has greatly increased our knowledge about objects orbiting the sun. There now exist significant mapping data for over 20 planets and satellites located through­ out the solar system. The National Aeronautics and Space Administration (NASA), the government agency responsible for developing space-related activities for the United States of America, charged the Planetary Cartography Working Group (PCWG) with the task of advising NASA of the best cartographic opportunities and methods associated with data returned from spacecraft exploration. The PCWG is made up of representatives of many different fields and institutions from government, industry, and universities. In early 1994 the PCWG published a ten-year plan outlining several recommendations and priorities projected for NASA's planetary cartography activities through 2003 [1]. This paper summarizes the main recommendations contained within that report, in an effort to disseminate 453 NASA goals and plans to the international cartographic community. Limited numbers of copies of the full report are available from the author (please address all such inquiries directly to him at the above address). The PCWG ten-year plan is the result of a large effort by numerous individuals over a period of several years. The author served as the Chairman of the PCWG during the two years which culminated in the final report. However. the ideas contained within the report are the result of input from many individuals; listed below are all of the authors who contributed to the final published report: James R. Zimbelman, Smithsonian Institution (Chair, 1991-1994) Raymond Batson. U.S. Geological Survey William V. Boynton, University of Arizona William Cannell, Environmental Research Institute of Michigan Merton E. Davies, RAND Corporation Frederick J. Doyle, Environmental Research Institute of Michigan Daniel M. Janes, Cornell University Baerbel Lucchitta, U.S. Geological Survey Harold Masursky, U.S. Geological Survey Peter J. Mouginis-Mark, Hawaii Institute of Geophysics, University of Hawaii R. Stephen Saunders, Jet Propulsion Laboratory Paul Schenk, Lunar and Planetary Institute Peter C. Thomas, Cornell University (Chair, 1988-1990) Steven H. Williams, University of North Dakota Sherman Wu. U.S. Geological Survey Joseph Boyce, NASA Headquarters Stephen Baloga. NASA Headquarters 2 Background Since 1962 more than 1600 planet and satellite maps have been published in the United States. Most of the maps are of the Moon (50%) and Mars (43%). representing 'the focus of most U.S. spacecraft efforts in the 1960s and 1970s. The production of lunar maps largely ceased after production of orthophotomosaics to support the Apollo 15. 16. and 17 missions. but the recent phenomenal success of the unmanned Clementine spacecraft in providing global coverage of the lunar surface [2] will undoubtedly result in new mapping products of the Moon in the coming years. The necessity for a balanced strategy of planetary mapping is best illustrated by considering the total solid surface area present within the solar system (see Figure 1). Viewed in this context, the land area of Earth is but a fraction of the total 1.6 billion square kilometers of available surface area. 454 NEPTUNIAN SYSTEM \ URANIAN SYSTEM PLUTO & Charon VENUS MARS Moon EARTH (land) EARTH (oceans) Figure 1: Surface area of solid planets and satellites in the solar system. The total surface area included above is about 1.6 billion square kilometers. The full report is divided into several sections, briefly summarized below. Following an Executive Summary in Part 1, Part 2 describes the diverse but fundamental uses of planetary cartographic data, both for use in any scientific study of the surface of a solar system object, and as the key to indexing all kinds of data on the surfaces of planets and satellites. Parts 3 and 4 describe the cartographic methods, spacecraft missions, and data that have and will provide information on planetary surfaces. Part 5 reviews the status of cartographic products that have been produced through 1992. The final part is a set of recommendations for planetary cartography from 1993 to 2003; these recommendations are'summarized in the next section. Two fundamental themes pervade the entire report: the need for a variety of digital products and the large volume of planetary data that should be generated during the next several years. Analysis of planetary data in general is increasingly dependent upon digital storage, display, correlation, and calculation. The need to record coordinates of features visible in images requires that many different map products be in digital form so they can be used in conjunction with a variety of geophysical and remote sensing data products. The sheer volume of planetary data anticipated through the end of the millennium requires a reevaluation of how data products are analyzed and archived. For example, data from the Magellan mission to Venus (31 alone have a a volume that exceeds all previous planetary digital 455 images combined. Careful organization will be required to keep future planetary data fully useful to the international community. 3 Recommendations The general recommendations of the report list the following priorities: 1) from 1993 to 1995 the mapping of Venus with Magellan radar data, 2) from 1994 to 1996 the mapping of inner solar system objects, 3) from 1996 to 2000 the mapping of Galilean satellites and Mars, and 4) from 1994 to 2003 the mapping of small bodies from a variety of missions. 3.1 Venus In the near future the planetary cartography effort should concentrate on the production of image and topographic maps of Venus using Magellan radar data. The immense quantity of data from Magellan represents a more complete global picture of Earth's Sister planet than presently exists for our own home planet, which will be of particular value for studies in comparative planetology (Figure 2). This res04rce is presently avallable to the global scientific community in archival form through Compact Disks (CDs) of Magellan data produced by NASA's Planetary Data System (PDS), and through the continuing release on CD of mosaiced and rectified full­ resolution image maps (FMAPs) by the U.S. Geological Survey. Photographic prints of FMAPs at 1:1.5 million scale are available for viewing in the NASA-sponsored Regional Planetary Image Facilities located throughout the world. Paper versions of selected products hopefully will also be available eventually through the U.S. Geological Survey. 3.2 Inner Sofsr System At the time of publication, the report briefly acknowledged the recent loss of the Mars Observer spacecraft and the consequent delay in new data from Mars. The Mars Global Surveyor (MGS) spacecraft should recover much of the science planned for Mars Observer; MGS is scheduled to begin data collection at Mars in early 1998 [4]. MGS instruments will provide global coverage of low-resolution images, altimetry, and thermal infrared spectra, plus selected ver'y-high-resolution images; these data are essential to providing a global context for understanding the Red Planet, and they now should result in a variety of new cartographic products later in this decade. The Mars Pathfinder engineering demonstration spacecraft should provide information from a landing site in the martian northern hemisphere in mid- 1997 [5], but these data likely will have extremely limited regional extent and tfius very little cartographic potential. While we wait for these new data from 456 Mars, the report recommends that present base maps of Mars should be refined with improved processing of existing Viking data. Figure 2: Hemispheric view of Venus compiled from Magellan radar images; centered along longitude 180. The report compilation date preceded the launch of the Clementine spacecraft to the Moon. The success of the Clementine spacecraft in global mapping of Earth's Moon in early 1994 [2] has produced an 11-wavelength imaging database [6] that is just beginning to be utilized fully. Along with the multi-spectral imaging, Clementine altimetry data provided the first global perspective of the relief and shape of the Moon I7]. A great wealth of cartographic products will result from these new data sets, which will form the geographic reference for interpreting geophysical and geochemical data planned for the Discovery-class Lunar Prospector mission approved by NASA in early 1995. 3.3 Galileo and future Mars missions The Galileo spacecraft will reach Jupiter in December of this year, going into orbit around the largest planet in the solar system. The incomplete deployment of the high-gain antenna on Galileo has greatly reduced the data transmission rate, but new data compression techniques should allow roughly 70% of the original science objectives to be met at the reduced rate.